Optimism flowed through the halls of the Buffalo Bills' practice facility on Dec. 31, the day after the Bills ended their 2018 season by scoring 42 points in a win against the Miami Dolphins in the team's highest output in more than two years.

Quarterback Josh Allen ended his rookie season by scoring five touchdowns (three passing and two rushing), helping to validate coach Sean McDermott's season-long mantra of growing and developing his young players through an otherwise fruitless campaign.

Allen, the No. 7 overall pick of last April's draft, entered the offseason eager to grow up alongside a young cast of skill-position players that included tight end Jason Croom (a 2017 undrafted rookie) and receivers Zay Jones (a 2017 second-round pick), Robert Foster (a 2018 undrafted rookie), Isaiah McKenzie (a 2017 fifth-round pick of the Denver Broncos whom the Bills claimed off waivers) and Ray-Ray McCloud (a 2018 sixth-round pick). Allen convened with some of his incumbent receivers for workouts this offseason and built a rapport with some of his young offensive linemen.

2019 Free Agency | Bills

"Consistency is key, especially in the league," Allen said Dec. 31. "Being able to have the same terminology, the same playbook, the same guys around you, that increases trust, increases the knowledge that you have in the system, allows you to go out there and not think about it too much and just kind of play the game."

Allen will have offensive coordinator Brian Daboll back for his second season -- if Daboll lasts the entire season, it will be the first time an offensive coordinator has strung together consecutive seasons in Buffalo since Nathaniel Hackett in 2013-14 -- but any idea that Allen would be given an opportunity to mature with the same group of players around him was misguided.

Instead, the Bills invested in a bevy of veterans to buttress almost every position around Allen, and it will be up to the second-year quarterback to lead a more experienced group and win in 2019.

With $80 million in salary-cap space entering his second full offseason on the job, general manager Brandon Beane injected the offense with 13 free-agent signings that will yet again change the complexion of an offense that had already undergone a makeover since Allen's arrival last spring.

Allen's surrounding offense changed drastically from the group he had in the second half of the Bills' 2018 season opener (when the implosion of Nathan Peterman forced McDermott to play Allen) to his final start in Week 17:

Buffalo's Changing Offense

The Bills' supporting cast around quarterback Josh Allen was fluid in 2018:

2018 Offense: Week 1

2018 Offense: Week 17

Pos.

Player

Pos.

Player

RB

LeSean McCoy

RB

LeSean McCoy

FB

Patrick DiMarco

FB

Patrick DiMarco

WR

Kelvin Benjamin

WR

Robert Foster

WR

Zay Jones

WR

Zay Jones

WR

Jeremy Kerley

WR

Isaiah McKenzie

WR

Andre Holmes

WR

Ray-Ray McCloud

LT

Dion Dawkins

LT

Dion Dawkins

LG

Vladimir Ducasse

LG

Wyatt Teller

C

Ryan Groy

C

Ryan Groy

RG

John Miller

RG

Ike Boettger

RT

Jordan Mills

RT

Jordan Mills

TE

Charles Clay

TE

Jason Croom

The Bills' offense, which had been on a historically poor pace through the first half of the season, showed promise after Allen returned from an elbow injury in Week 12. It ranked 12th in the NFL the final six games, averaging 22 points per game, and Allen's Total QBR ranked 13th as the Bills went 3-3.

Even so, the Bills' 6-10 finish clearly was not encouraging enough for McDermott and Beane to take a passive approach to free agency and wait to build through the draft. McDermott fired wide receivers coach Terry Robisikie and offensive line coach Juan Castillo, and Beane focused the vast majority of his $50 million in free-agency spending on the offense.

Now, Allen's projected 2019 offense barely resembles the group he joined early last season:

At least two of the Bills' top four wide receivers should be new players in 2019, and at least three starters along the offensive line -- and possibly all five -- could be different. In particular, the starting guard spots appear to be a wide-open competition among Wyatt Teller and three newcomers.

What the Bills do with their No. 9 overall pick in the draft next week could further influence the starting offense, potentially adding a left tackle or wide receiver, and put pressure on Allen to pull it all together.

"Josh has his own work to do," McDermott said Monday. "He has a lot of work to do in that regard to develop the rapport with the receiving corps, whether it's tight ends, wide outs, backs. That'll be important."